DE19958934A1 - Motor control unit for controlling switching element of each switching arm and regulating current supplied to motor in vehicle, has high voltage and low voltage switching units and temperature detection diodes - Google Patents

Abstract

The unit has a first switching unit which operates from a high potential, and a second switching unit which is supplied from a low potential. The switching units are joined in series. There are also temperature detection diodes in the vicinity of the unit. The three phase AC motor (2) is supplied with AC power using a control unit (3) for controlling the switching operation of each switching element, to control the current to the motor. A semiconductor element (19) is arranged with a P-N transition in the vicinity of the switching element and is connected with a constant current circuit (18). In addition an overheating protection unit (8,9) is provided, in order to determine the temp. of the switching element, by detecting a forward voltage value between the P-N transition of the semiconductor element and to bring the switching element in an OFF position. If on the basis of the detected of the switching element is decided, that the switching element is found to have an overheated condition.

Description

Field of the Invention

The present invention relates to an engine control unit, which uses an engine Drives power conversion semiconductor, and in particular the overheating protection of the power conversion semiconductor and the temperature control of the engine control unit.

Description of the prior art

A first example of a conventional engine control unit provided with an overheating protection function is shown in FIG. 14. In the first example, as shown in Fig. 14, a three-phase AC motor is used as a motor and an inverter is used as a power converter.

In Fig. 14, a reference numeral denotes an engine control unit 1 A, a reference numeral 2 is a motor 3A, a control calculation unit 4A and a power conversion semiconductor. The power conversion semiconductor 4 A is provided with three-phase switching arms (U phase arm, V phase arm and W phase arm), an overheating identification device 8 A and an overheating protection device 9 A. The U phase arm, which is one of the switching arms, consists of a switching element 5 a of the upper arm, a switching element 5 b of the lower arm, a free-running element 6 a of the upper arm, a free-running element 6 b of the lower arm, a gate switching element 7 a of the upper arm, a gate switching element 7 b of the lower arm and thermistors 10 and 11 . The V phase arm and the W phase arm have the same structure as the U phase arm. A bipolar transistor is used here for the switching element. In the drawing, C, G and E show a collector, a gate and an emitter, respectively.

The engine control unit 1 A generally converts DC power from an electric power unit (not shown) into an AC power and supplies it to the motor. 2 The conversion from direct current energy to alternating current energy is carried out by switching the switching elements, which consist of a power element of the power conversion semiconductor 4 A. The power elements consist of the switching elements and the free running elements. A gate drive signal, which is generated in the control calculation unit 3 A for switching, is connected to the gate G of the switching elements via the gate switching elements. When the switching elements are electrified by switching, they generate heat due to internal losses. Overheating can destroy the switching elements. In order to avoid the possible destruction of the switching elements, overheating protection is provided by monitoring the temperature of the switching elements and the signal flowing from the control calculation unit 3 A to the gates of the switching elements being interrupted (gate interruption) when the temperature reaches a predetermined level , and by interrupting the electrical current sent to the switching elements. A protective function operating alarm signal is sent to the controller 3 A calculation unit when the overheat protection is performed. In the drawing, an overheating identification means determines 8 A by a signal from the thermistor 10 if the temperature detection and the gate interrupt are necessary or not. The signal for interrupting the gate is generated in the overheating protection device 9 A in order to effect the gate interruption by the gate switching elements 7 a and 7 b. The thermistor 10 is located near the switching elements to properly reflect the temperature of the switching elements.

Another thermistor 11 is arranged on the circumference of the switching elements as a device for informing the control authorization unit 3 A about the temperature of the switching elements. In the control calculation unit 3 A, the temperature information of the switching elements from the thermistor 11 is determined, for example, by a microcomputer or an A / D converter. A gate drive signal is operated with this temperature information (signal), so that the temperature of the switching elements is not raised excessively.

As a second conventional example, Japanese Patent Application Laid-Open (Kokai) No. Hei 10-21079 discloses a control unit for protecting switching elements from overheating by using a temperature signal from a power conversion semiconductor. In this second conventional example, an engine control unit for performing overheating protection is applied to an electric vehicle. Fig. 15 shows this second conventional example.

In Fig. 15, reference numeral 2 denotes an engine, reference numeral 12 is a battery, 13 is a power converter, 14 wheels, 15 is a power conversion ECU (electronic control unit), 16 is an accelerator pedal, and 17 is a temperature sensor.

The power converter 13 is connected to the battery 12 serving as a power unit, and the motor 2 for driving the vehicle is connected to the power converter 13 . The driving force of the engine 2 is transmitted to the wheels 14 via an axis of rotation and a differential gear to serve as the driving force of the vehicle. The power converter 13 is provided with the power conversion semiconductor. Further, the power converter 13 is controlled by the power conversion ECU 15, and the power conversion semiconductor within the power converter 13 starts switching operation in response to a gate drive signal input from the power conversion ECU 15 . With this switching operation, the direct current energy supplied by the battery 12 is converted into an alternating current energy that is to be supplied to the motor 2 .

The power conversion ECU 15 is connected to an accelerator pedal 16 and is configured to detect an amount of pressure as an accelerator opening A% when a driver steps on the accelerator pedal 16 . However, it should be noted that the accelerator opening is 100% when the accelerator is fully depressed.

The power converter ECU 15 is also connected to the temperature sensor 17 , which is located inside a housing of the power converter 13 , in order to determine the temperature INV-T of the switching elements. Furthermore, the power converter ECU 15 determines the change amount of the element temperature per unit time based on the element temperature INV-T to enable the temperature change rate to be ΔT / Δt.

The power converter ECU 15 determines a torque to be output from the engine 2 according to the accelerator opening A% and converts the found torque into a torque command *. Furthermore, the following two types of limiting rates (a first limiting rate α, a second limiting rate β) multiplied by the torque command T form the regulated torque command T *. The first limitation rate α is determined based on the element temperature INV-T. The first limit rate α is 100% when the element temperature INV-T is below a limit start temperature Ti. If the element temperature INV-T is higher than the limit start temperature Ti, then the first limit rate α, which corresponds to the element temperature INV-T at this time, is multiplied by the torque command T *. When the element temperature INV-T reaches a zero power temperature T2, the first limiting rate is α 0 and the torque command T * is also 0.

The second limiting rate β is based on the Temperature change rate ΔT / Δt determined. The second Clipping rate is used; if the element temperature INV-T is above the limit start temperature Ti. If the Temperature change rate AT / Δt below a first Is the reference value δ1, the second limiting rate is α 100%. If the temperature change rate ΔT / Δt is higher than the first Is the reference value δ1, then the second limiting rate β, which corresponds to the rate of change ΔT / Δt at that time with multiplied by the torque command T *. If the Temperature change rate ΔT / Δt greater than the second reference δ2, then the second limiting rate is β 0 and Torque command T * is also 0.

The power converter ECU 15 observes the regulated torque command T * obtained from the above process and a command value I * of a motor electrification current corresponding to the regulated torque command T *. The generated torque of the motor 2 is controlled to match the regulated torque command T * by switching the switching elements of the power conversion semiconductor based on this current command value I *.

As described above, the switching element temperature is high in the second conventional example and if they rises quickly, then the switching elements in front of one Protected against overheating by essentially the Torque command is regulated. If, on the other hand, the Temperature of the switching elements is high, but not quickly the torque command does not have to rise as quickly how to regulate the rapid rise. So it is possible to switch the switching elements before overheating protect while the torque according to the extent of Temperature is regulated.

According to the first conventional example, it is possible to use one Protection against overheating by stopping the switchover (gate Interruption) and overheating protection by a Temperature rise monitoring relative to that Temperature rise of the switching elements in the To provide power conversion semiconductors.

However, the thermistor 10, which serves as the temperature sensor for an overheating protector, from the thermistor 11 serving as the temperature sensor, the temperature of the switching elements transfers to the control calculation unit 3 A differs according to the first conventional example. It is also difficult to cause the temperature of the switching elements indicated by the thermistor 10 to exactly match that of the switching elements indicated by the thermistor 11 due to the distance of the switching elements from their tips, as in FIG Arrangement and distribution of the electrical characteristics of each sensor seen. Therefore, if it is necessary to generate a gate control signal for switching the power conversion semiconductor 4 A for overheating protection via temperature monitoring by the thermistor 11 before the overheating protection is activated by the thermistor 10 , it is necessary to absorb the distribution of the sensor, by setting a threshold temperature start operation of the gate control signal to a lower value. However, if the threshold temperature is thus set to the lower value, there is some possibility that the overheating protection process will be carried out frequently, even in normal operation, and therefore it is not practical. On the other hand, if the threshold temperature is set to a normal value (not low), there is a certain possibility that the overheat protection from the thermistor 10 is performed before the start of the overheat protection process, depending on the distribution (dispersion) of the sensor) and the switching operation of the switching elements stops to interrupt the control. Such a property is not desirable in the engine control unit of the present invention.

Even if, according to the second conventional example, the Switching element temperature of the power conversion semiconductor suddenly increases, it is possible to prevent yourself the switching element overheats by not only one Torque command of the engine is regulated, but also a Electrification current command according to a rate of change per unit time of the switching element temperature. The regular amount of the torque command is increased or decreased by the suitable torque control depending on whether the Switching element temperature is high or low, to provide.

However, in the second conventional example, when a temperature signal of the switching element to be connected to the power converter ECU 15 changes rapidly for some reason, such as a wire break or a failure of the switching element temperature sensor, the torque command is largely controlled because one Rate of change per unit time of switching element temperature is large, resulting in a sudden change in the generating torque of the motor. This property is not desirable in a vehicle engine control unit in an electric vehicle because it has a poor impact on the continuity of control and also affects the vehicle response system.

Summary of the invention

It is therefore an object of the present invention to Engine control unit to provide all of the Disadvantages of the prior art mentioned above eliminates and quickly and accurately the temperature of a Switching element can detect that a power element of a Power conversion semiconductor forms, and in a more suitable Way can prevent the switching element from overheating, which ensures the continuity of the control.

According to the present invention is an engine control unit provided, comprising a first switching element, which on a High potential side is arranged, a second switching element, located on a low potential side, one Multiple phase of switching arms that are the first switching element and connect the second switching element together in series, and connected in parallel to a DC power input is about an AC motor with an AC power from between each switching element of each switching arm supply a control calculation unit for controlling the Switching each switching element to a current of Motor control, and being a semiconductor element with a P-N junction located near the switching element and is connected to a constant current circuit, and wherein overheating protection is provided to the temperature of the switching element by detecting a Forward voltage value between the P-N junction of the  Detect semiconductor, and the switching element in an OFF Condition brings when based on the detected temperature of the switching element is judged that the switching element in an overheating condition.

The control calculation unit further comprises one Current command value calculating means for calculating a Current command value sent to the motor, one Current control device for controlling a current supplied to the Motor is sent based on the current command value, and a monitoring device for entering the temperature of the Switching element and the current command value, for monitoring the Relationship between the switching element temperature and the Current command value in a time sequence and for controlling the Current command value to cause the movement of the Motors in the event of a failure, for example one Damage to the semiconductor element or a wire break, changed in a moderate way.

Another is in place of the monitoring device Monitoring device for entering the engine temperature, the Switching element temperature and the current command value to Monitoring the relationship between the engine temperature, the Switching element temperature and the current command value in one temporal sequence, and to control the current command value to to cause the movement of the motor to fall a failure, for example a confirmation of the Semiconductor element and a wire break, in a moderate manner changed, provided.

The control calculation device is also equipped with a Current calculation device for calculating a current value, which is sent to the switching element based on the Switching element temperature and one Output terminal voltage value of the switching element.  

Furthermore, the overheating preventing device designed to match the forward voltage value of the Semiconductor element beforehand at the fixed temperature save so that it can detect the change if there is the absolute size of the switching element temperature changed.

The overheating protection device is designed to protect the Switching element temperature to the control calculation unit in in the form of an analog signal or to send information in terms of whether the overheating protection of the switching element is now is currently running or not, to the Control calculation unit in the form of a digital signal to send. It is also designed to be the highest Detect temperature of each phase of the switching element and an assessment based on this highest temperature to execute.

The semiconductor element is also within the tip area arranged where the switching element is formed, or in the Near the tip area.

For example, a diode is used as the semiconductor. For example, a bipolar transistor is used for Switching element used and the collector-to-emitter Voltage value of the bipolar transistor as the switching element is detected by the voltage detection device.

The above and other tasks, features and advantages of The present invention will be apparent from the following Description in connection with the enclosed Drawings.

Brief description of the attached drawings

The drawings show:  

Fig. 1 is a block diagram of a motor control unit according to a first embodiment of the present invention;

Fig. 2 is a view explaining the first embodiment;

Fig. 3 is a view explaining a second embodiment;

Fig. 4 is a block diagram of a motor controller according to the third and fourth embodiments;

Fig. 5 is a block diagram of a motor control unit according to a fifth embodiment;

Fig. 6 is a view showing an example of a power element that is used in the sixth embodiment;

Fig. 7 is a block diagram of a motor control unit according to a seventh embodiment;

Fig. 8 is an internal block diagram of a temperature monitoring device in the seventh embodiment;

Figure 9 is a view showing a time gain table within the temperature monitoring device of the seventh embodiment.

FIG. 10 is a block diagram of a motor control unit according to an eighth embodiment;

FIG. 11 is an internal block diagram of the temperature monitoring device according to the eighth embodiment;

FIG. 12 is a block diagram of a motor control unit according to a ninth embodiment;

FIG. 13 is a view explaining the operating principle of the ninth embodiment;

FIG. 14 is a block diagram showing an engine control unit as a first conventional example; and

Fig. 15 is a block diagram showing a Fahrzeugmotor- control unit as a second conventional example.

Description of the preferred embodiments First embodiment

A first embodiment of a motor control unit according to the present invention is explained below with reference to FIGS . 1 and 2.

Fig. 1 is a block diagram showing a construction of an example of a motor controller of the present invention. Here, an engine control unit in a vehicle is explained, but it should be noted that the engine control unit can also be used for other vehicles.

In Fig. 1, reference numeral 1 denotes an engine control unit in a vehicle, reference numeral 2 denotes a motor, 3 is a control computing unit 4 and a power conversion semiconductor in a vehicle. The power conversion semiconductor 4 in the vehicle (an on-vehicle power conversion semiconductor) serving as an energy conversion unit is provided with three-phase switching arms (U-phase arm, V-phase arm and W-phase arm), an overheating identification device 8 , an overheating protection device 9 , and a constant current circuit 18 , which is designed to send an electrical current to a temperature detection diode (described below). The U-phase arm, which is one of the switching arms, consists of a switching element 5 a of the upper arm, a switching element 5 b of the lower arm, a free-running element 6 a of the upper arm, a free-running element 6 b of the lower arm, a gate Switching element 7 a of the upper arm, a gate switching element 7 bm of the lower arm and the temperature detection diode 19 . The V-phase arm and the W-phase arm have the same structure as the U-phase arm. A bipolar transistor is used here for the switching element.

A switching element and a free-wheeling diode form an energy or power element. This means that two power elements are connected in series per phase of the three-phase alternating current. The side that is on a high potential side of the DC power input is referred to as "an upper arm", and that on a low potential side is referred to as "a lower arm". The temperature detection diode 19 serving as a temperature sensor for the switching element that constitutes the power element is formed on the same board as the power element.

The overheat identifier 8 inputs a forward voltage value generated between the anode and the cathode (PN junction) of the temperature detection diode 19 , which is a semiconductor element with the PN junction, and judges whether overheating protection by reading changes in the input forward voltage value should be executed or not. This overheat identification device 8 outputs an interruption indication signal (hereinafter referred to as "a gate interruption indication signal") of a switching signal (gating signal) to the overheat protection device 9 when it judges that the overheat protection should be performed. The overheating identification device 8 and the overheating protection device form the overheating protection device.

The overheating protection device 9 outputs a signal that causes the gate switching element to turn off to the gate switching element when it inputs the gate open indication signal from the overheating identification device 8 , and interrupts the transmission of the gating signal from the Control calculation unit 3 to the switching element.

The engine control unit 1 in a vehicle (hereinafter also referred to as an on-vehicle engine control unit) of the first embodiment is formed by the on-vehicle power conversion semiconductor 4 and the control calculation unit 3 with the above-mentioned structure.

Operation of this embodiment will be as follows described.

The on-vehicle power conversion semiconductor 4 is connected to an electric power unit (not shown) and converts an input DC power into an AC power and sends it to the motor 2 . The conversion from the direct current energy to the alternating current energy is carried out by switching the switching element that forms the power element of the on-vehicle power conversion semiconductor 4 . In the control calculation unit 3 , the command value of the electric current to be electrified is calculated to enable the motor 2 to perform the required movement, and the switching signal for switching the switching element ON / OFF is generated to cause that the current of the current command value flows. The switching signal (gating signal) is transmitted to a gate G of the upper and lower switching elements of each phase.

When electricity is turned on by a switching operation, the switching element generates heat due to the internal losses. There is a possibility of the switching element failing to overheat when the switching element generates heat. Therefore, the overheat identification device 8 detects the temperature of the switching element and judges whether or not the gate interruption of the switching signal should be performed to provide the overheating protection. When the overheat identification device 8 judges that the gate interruption should be performed, it sends a gate interruption indication signal to the overheat protection device 9 . Upon receipt of the gate open indication signal, the overheat protection device 9 sends the gate open signal to the gate switch to close the gate switch and stops transmitting the gate signal to the switching element.

The temperature detection of the switching element by the overheat identification device 8 is carried out as specified below. A constant current if flowing from a constant current circuit 18 flows into the anode side of the temperature sensing element 19 and out of the cathode side. The electrification current at this time is referred to as forward current in view of the polarity when it flows into the temperature detection diode 19 . Furthermore, a potential difference generated between the anode and the cathode of the temperature detection diode 19 is referred to as a forward voltage vf. The overheat identification device 8 is connected to the anode and the cathode of the temperature detection diode 19 and inputs the forward voltage vf.

A characteristic curve between the forward voltage Vf and the forward current if of the temperature detection diode 19 is shown in FIG. 2. That is, the forward voltage vf relative to the forward current if changes depending on the transition temperature Tj of the temperature detection diode 19 . The forward voltage drops relative to an increase in the transition temperature Tj.

The forward voltage Vf when a constant forward current if is sent to the temperature detection diode 19 has such characteristics as shown in FIG. 3 relative to the transition temperature Ti. That is, the forward voltage vf decreases as the transition temperature Tj increases. Accordingly, when changes in the forward voltage vf of the temperature detection diode 19 to which a constant forward current is sent are read, it is possible to detect the change in the transition temperature Tj of the temperature detection diode 19 .

That is, the overheat identification device 8 inputs the forward voltage vf of the temperature detection diode 19 and detects changes in the transition temperature Tj of the temperature detection diode 19 . In this case, it is possible to read the transition temperature Tj of the temperature detection diode 19 as the switching element temperature by placing the temperature detection diode near the switching element and by setting the forward current if of the temperature detection diode 19 to a lower value at which the diode itself is not overheated.

It is thus possible to control the switching element temperature Sending a constant forward current to the Temperature sensing diode on the same board as the power element formed and near the Switching element is arranged, and by reading the  Detect forward voltage of the temperature detection diode. Because this temperature detection is much faster than that through a thermistor and the temperature rise of the Switching element detected exactly within a short time becomes, it is possible to overheat protection characteristics to improve the switching element.

Second embodiment

It may also be advisable to have the overheat identification device 8 store the forward voltage value of the temperature sensing diode 19 at the fixed temperature.

A second embodiment is explained below according to FIG. 3. The forward voltage at temperature Tj0 is Vf0. As a result of a subsequent change in the switching element temperature when the detected forward voltage value is Vf1, the current temperature Tj1 is determined as the temperature change corresponding to {Tj0- (Vf1-Vf0)}. Now, since a change amount Avf of the forward voltage value is constant relative to a change rate ATj of the transition temperature regardless of the transition, it is possible to grasp the absolute magnitude of the transition from time to time regardless of how the forward voltage changes if the absolute value of the transition temperature is determined relative to a certain forward voltage value. Therefore, if the forward voltage value of the temperature detection diode 19 is stored at a fixed temperature, for example at a temperature at which the switching element temperature can be recognized at room temperature without the help of the temperature identification device 8 A, it is possible to determine the transition temperature, that is to calculate the absolute size of the switching element temperature quickly and accurately, even if the switching element temperature changes thereafter.

Third embodiment

As shown in FIG. 4, it may also be advisable to add a function that transmits the temperature information (a signal) of the switching element as an analog signal to the control calculation unit 3 to the overheating control device.

Namely, when the forward current is sent to the temperature detection diode 19 from a constant current circuit 18 , the forward voltage Vf of the temperature detection diode 19 is input to the overheat identifier 8 at this time. In the overheat identification device 8 , the switching element temperature in the overheat identification device 8 is calculated in the same manner as in the embodiments 1 and 2. The overheat identification device 8 further judges, based on the calculated switching element temperature, whether the gate interruption of the switching signal should be carried out for overheating protection or not. When the execution of the gate interruption is judged, the overheat identification device 8 sends the gate interruption indication signal to the overheat protection device 9 . At the same time, the overheating identification device 8 sends the absolute size of the switching element temperature to the control calculation unit 3 as an analog signal. The control calculation unit 3 generates the switching signal of the switching element that constitutes a power element by using the temperature information of the input switching element. Since the temperature information of the switching element is the same as that used within the overheat identification device 8 a to judge conditions as to whether the gate open is executed or not, there is no possibility that during the control operation of the on-vehicle Motor control unit will interrupt the control movement from the gate break for overheating protection and will seriously affect vehicle operation if the switch signal is generated to control the heat generation of the switch element before the switch element temperature reaches a threshold temperature for executing the gate break .

It should be noted that the switching element temperature information sent from the overheating identification device 8 to the control calculation unit 3 , the amount of change per unit time of the switching element temperature, an increase or decrease in the switching element temperature after the on-vehicle engine control unit 1 is started or a combination thereof.

Fourth embodiment

A function of sending information about whether overheating protection is being performed or not to the control calculation unit 3 as a digital signal can be added to the overheating identification device 8 .

Namely, the overheating identification device 8 judges on the basis of the calculated switching element temperature whether the gate interruption of the switching signal should be carried out for overheating protection or not. When the execution of the gate interruption is determined, the overheat identification device 8 sends a gate interruption indication signal to the overheat protection device 9 and transmits information as to whether the overheat protection is being executed or not to the control calculation unit 3 as one digital signal. The digital signal as given here can be a high / low binary level of a logic element or the serial communication by a binary level of a time combination.

Furthermore, the control calculation unit 3 executes a predetermined operation to ensure safety of the vehicle movement until the overheating protection is removed, based on the input information as to whether the overheating protection is currently being carried out or not, and controls, for example, the activation of a fan or of a fan for heat radiation so that the overheating protection can be removed soon. The predetermined movement includes a warning to the driver by lamps, speech and the like, for example an overheating warning display in a motor-driven vehicle. When a drive motor is controlled in a hybrid vehicle, the motor output is also executed while controlling electricity for overheating protection and movement is expected for output control of an engine, predicting the lack of output of the motor.

Thus, the information sent from the overheating identification device 8A to the control calculation unit 3 can indicate whether the overheating protection has already been carried out, the overheating protection has been carried out more than a fixed number of times, the overheating protection by a fixed value than the threshold temperature being executed has risen, the overheat protection will be executed after a fixed time in the future, or a combination thereof.

Fifth embodiment

An embodiment in which the overheating protection can be performed depending on the heat generation conditions of each phase of the switching element will be explained with reference to FIG. 5. In each phase of the arms U, V and W, the temperature detection diode , as shown in Fig. I, is formed on the same board as the power element. The V phase arm and the W phase arm have the same structure as the U phase arm, but different alphabetical names are given to them in the figure.

The temperature detection diodes 19 a, 19 b and 19 c of each phase are connected in parallel to the overheating identification device 8 and the temperature detection diodes 19 a, 19 b and 19 c of each phase are connected to a constant current circuit 18 . The temperature detection diodes 19 a, 19 b and 19 c of each phase are connected in parallel to the overheating identification device 8 because these can be a reference potential and four input lines if the forward voltage Vfu, Vfv and Vfw of the temperature detection diodes 19 a, 19 b and 19 c is recorded. However, if wiring is required to sense the forward voltage Vfu, Vfv and Vfw, the type of wiring is not important.

The operation of this embodiment will now be as follows described.

The overheat identification device 8 inputs the forward voltage Vfu, Vfv and Vfw to the respective temperature detection diodes 19 a, 19 b and 19 c and then detects changes in the transition temperature Tju, Tjv and Tjw of the respective temperature detection diode 19 a, 19 b and 19 c. In this case, if each temperature detection diode 19 a, 19 b and 19 c is formed in the vicinity of the switching element and the forward current if of the temperature detection diodes 19 a, 19 b and 19 c is set to a lower value so that the diodes themselves are not overheated , then the transition temperature Tju of the U-phase temperature detection diode 19 a can be read as the U-phase switching element temperature, the transition temperature Tjv of the V-phase temperature detection diode 19 b can be read as the V-phase switching element temperature or the transition temperature Tjw of the W-phase temperature detection diode 19 c can be read as the W-phase switching element temperature.

If, as can be seen from the above description, at the temperature detection diode on each switching arm of each phase the same board as the power element is formed, a fixed forward current to the temperature sensing diode is sent and the forward voltage of the Temperature sensing diode is read, it is possible to Detect switching element temperature of each phase exactly. By Using the switching element temperature as the standard of Assessment for the maximum temperature within the Switching element of each phase, even if there is any deviation in the heat generating condition of the switching element each Phase is present, it is therefore possible to Overheating protection according to the highest overheating temperature of the switching element to perform exactly.

Sixth embodiment

As shown in FIG. 6, a unit of a power element consists of a tip region, which forms the switching element, and another peak region, which forms a free-wheeling diode, on the semiconductor board. The switching element is formed by arranging a plurality of switching elements in parallel, which are designed to emit a small amount of current. Accordingly, it is desirable to detect the temperature within the peak area that constitutes the switching element with respect to heat generation of the electrified switching element. Thus, by placing the temperature detection diode close to the tip area of the switching element or by forming it within the tip area, it becomes possible to detect the peak temperature of the switching element for accurate overheating protection without delaying heat conduction.

Seventh embodiment

An on-vehicle engine control unit in combination with a control calculation unit 3 including a temperature monitor therein will be described below with reference to FIGS. 7 and 8.

Fig. 7 is a block diagram of the On-Vehicle- engine control unit according to a seventh embodiment. In FIG. 7, reference numeral 3 is a control calculation unit which is provided with a temperature monitoring device 20 , a current command calculation device 21 and a current control device 22 . An on-vehicle power conversion semiconductor 4 has the same structure as in FIG. 5.

Fig. 8 is an internal block diagram of the temperature monitoring means. In the figure, reference numeral 30 is an absolute value circuit, reference numerals 31 a, 39 and 46 are output devices for a one-time calculation precycle, 31 b is an output device for a two-time calculation precycle, 31 m is an output device for an m-time calculation precycle, 32 is an adder, 33 a gain calculation card, 34 a maximum value output device, 35 and 61 a minimum value output device, 36 , 42 , 50 and 58 constant output devices, 38 and 41 coefficient multipliers, 37 , 40 43 , 47 and 53 subtractors, 44 and 45 multipliers, 48 , 54 and 55 comparators, 49 and 57 gain calculation output devices, 51 and 59 time gain tables, 52 and 60 logic selective switches and 56 a logic unit.

The operation of the engine control unit is as follows described.  

As shown in Fig. 5, the forward current if is sent to each of the temperature detection diodes 19 a, 19 b and 19 c and the overheat identification device 8 inputs the forward voltage Vfu, Vfv and Vfw of each of the temperature detection diodes 19 a, 19 b and 19 c calculates the temperature Tju, Tjv and Tjw for each phase of the switching element. In this case, as shown in the second embodiment, it is possible to accurately calculate the switching element temperature as an absolute value by storing the forward voltage Vfu, Vfv and Vfw of each temperature detection diode 19 a, 19 b and 19 c at a fixed temperature, for example at the temperature at which the switching element temperature can be recognized at a room temperature without the help of the overheating identification device 8 . The overheat identification device 8 judges whether or not the gate interruption should be performed for overheating protection based on the calculated Tju, Tjv and Tjw, and sends a signal to the overheating protection device 9 when it is judged that the gate interruption is performed should be. Furthermore, the switching element temperature Tju, Tjv and Tjw is output as the switching element temperature signal of each phase from the overheat identification device 8 .

Then, when the preset current command I * output from a current command calculator 21 and the switching element temperature Tju, Tjv and Tjw of the temperature monitor 20 are input, the upper and lower limit limit LMT (I *) for the current command becomes on the current command calculator 21 is output.

As shown particularly in FIG. 8, when the switching element temperature Tju, Tjv and Tjw is input to the maximum value output device 34 , the maximum value Tjmax of Tju, Tjv and Tjw is selected and output. The subtractor 37 subtracts the maximum value Tjmax from a constant Tmax-Tj that is output from the constant output device 36 and outputs a temperature margin T jmargin. The constant Tmax-Tj is set to a value corresponding to the temperature that the switching element is damaged by overheating. Then, Tjmargin is multiplied by Ka in the coefficient multiplier 38, and the value corresponding to the upper and lower limits of electricity to be sent to the motor 2 is output. Namely, the current is limited according to the temperature margin Tjmargin, and the gain is determined by the amount of the temperature rise, the heat radiation behavior and the like of the switching element relative to an amount of an electric current.

Furthermore, the temperature margin Tjmargin is output to an output device 39 for a one-time calculation pre-cycle and the temperature margin of the cycle immediately before the calculation cycle Tjmargin (n-1) is output therefrom. The calculation cycle treats the course of time discretely and the cycle is shown with Δt. The temperature margin of the current cycle is shown as Tjmargin (n) and the temperature margin of the m-th cycle before the calculation cycle is shown as Tjmargin (nm). Referring to subtractor 40 , the temperature margin of the cycle immediately before cycle Tjmargin (n-1) is subtracted from the temperature margin of the current cycle Tjmargin (n) and a rate of change in temperature margin per cycle Δt (Tjmargin (n) -Tjmargin ( n-1) / Δt = Δtjmargin / Δt is output, then the rate of change (Δtjmargin / Δt) is input to the coefficient multiplier 41 and multiplied by the gain Kb. In the subtractor 43 , the output of the coefficient multiplier 41 is output from the constant. Output device 42 subtracts to output 1.0-Kb × (ΔTjmargin / Δt) Next, the output of coefficient multiplier 38 is multiplied by the output of subtractor 43. Multiplication of 1.0-Kb × (Δtjmargin / Δt) corresponds to an adjustment of the value, which corresponds to the upper and lower limit of electricity (Kb × Tjmargin) that is sent to the motor 2 rden, according to the rate of change of the temperature margin per cycle Δt (ΔTjmargin / Δt). That is, when the decrease in the temperature margin is large, the upper and lower limit limits of electricity are set to a smaller value, while when the increase in the temperature margin is large, the upper and lower limit limits are set to a larger value.

On the other hand, the preset current command I * output from the current command calculator 21 is input to an absolute value circuit 30 upon feedback, and the absolute value | I * | of the preset current command I * is issued. If | I * | each calculation previous cycle output means 31 is input to a- 31 m, respectively | I * | (n-1), | I * | (n-2),. . . | I * | (nm) output. Next, | I * | (n-1), | I * | (n-2),. . . | I * | (nm) and | I * | (n) are input to adder 32 to give the total Σ | I * | to investigate. If Σ | I * | is input to the gain calculation card 33 , then a setting gain amount corresponding to the total sum Σ | I * | spent. In multiplier 45 , the output of multiplier 44 is multiplied by the output from the gain calculation card for output. That is, this output corresponds to setting the upper and lower limit limits of electricity to be sent to the motor 2 according to the amount of the total Σ | I * | of the absolute value of the preset current command I * for the term of the past mx Δt. The gain calculation map 33 is determined by the heat radiation behavior and the like with respect to the amount of current.

Furthermore, the switching element temperatures Tju, Tjv and Tjw are input to a minimum value output device 35 and the minimum value Tjmin of Tju, Tjv and Tjw is output. Then, the difference between the output Tmax of the maximum value output device 34 and the output Tjmin of the minimum value output device 35 , that is, the difference (Tjmax-Tjmin) between the maximum and minimum temperature of the switching element of each phase is output. Next, when the output of the subtractor 53 is input to the comparator 54 , a judgment is made which is larger: (Tjmax-Tjmin) or the constant Ta. If (Tjmax-Tjmin) <Ta, a logical 1 is output, and if (Tjmax-Tjmin) is Ta, then a logical 0 is output. Furthermore, the output Tjmin of the minimum value output device 35 is output to the comparator 55 for a comparison with the constant Tb. If Tb <Tjmin, a logic 1 is output, and if Tb <Tjmin, a logic 0 is output. Next, 1 or 0 is output in a logical operation by an OR logic unit 56 .

The output of the OR logic calculation element 56 is input to a gain calculator 57 , and the value corresponding to the upper and lower limit limit of the current to be sent to the motor 2 is output. The gain calculator 57 consists of the constant output device 58 , the time gain table 59 and the logic selector switch 60 . The gain calculator 57 is designed to output the value Ga of the constant output means 58 when the input logic is 0 and to output the value Gb (t) of the time gain table 59 when the input logic is 1 . Fig. 9 shows the time gain table 59 with details. In Fig. 9, the lateral axis shows the time t from an event generation time, and the vertical axis shows the gain output value. That is, the time when input logic on the gain calculator changes from 1 to 0 is the event generation time and the gain output value Gb corresponding to the elapsed time from that point is output. Referring to the gain Gb in Fig. 9, the value is immediately after the event generation Ga and gradually decreases to 0. This is because if a failure, for example a diode failure or a signal wire break occurs during the signal transmission from the temperature detection diodes 19 a- 19 c through the overheating identification device 8 to the temperature monitoring device 20 , the sudden increase in the temperature difference (Tjmax-Tjmin) between the switching elements of each phase and a sudden drop in the minimum temperature Tjmin is automatically detected and as a result the effect of the motor 2 can be controlled in a moderate manner without affecting the control continuity.

If a rate of change in temperature margin (ΔTjmargin / Δt), which is the output of subtractor 40, is input to the output device for a one-time calculation pre-cycle, then the rate of change in temperature margin of the cycle immediately before the cycle (ΔTjmargin / Δ (n- 1)) issued. Then, in the subtractor 47, the rate of change of the temperature margin of the cycle immediately before the cycle (ΔTjmargin / Δ (n-1)) is subtracted from the rate of change of the temperature margin of the current cycle (ΔTjmargin / Δ (n)) and the rate of change component of the rate of change of the temperature margin per cycle Δt is output. Then, in the comparator 48, the change component of the rate of change of temperature margin, which is the output of the subtractor 47 , and the constant Da are compared to find out which is larger, if (the rate of change of rate of change of the temperature margin) <the constant Da, then a logical 1 is output, and if (the change component of the rate of change of the temperature margin) is Ga, a logical 0 is output. The output of the comparator 48 is input to the gain calculator 57 , and the value corresponding to the upper and lower limit limit of the current to be sent to the motor 2 is output. The gain calculation device 49 consists of a constant output device 50 , a time gain table 51 and a logic selector switch 52 . The gain calculator 49 outputs the value Gc of the constant output device 50 when the input logic is 0 and the value Gd (t) of the time gain table 51 when the input logic is 1 . The timing gain table 51 is shown in detail in FIG. 9. That is, the time when the input logic on the gain calculator changes from 1 to 0 is regarded as the event generation time, and the gain output value Gd corresponding to the subsequent elapsed time is output. The gain Gb has the value Gc immediately after the event generation and gradually decreases to 0. This is because if there is a failure, for example a diode failure, a signal wiring break or the like in the signal transmission from the temperature detection diodes 19 a- 19 c via the overheating identification device 8 to the temperature monitoring device 20 , the sudden increase in the difference of the maximum Temperature between the switching element of each phase can be detected automatically and, as a result, the effect of the motor 2 can also be controlled in a moderate manner without affecting the control continuity.

Next, the minimum value output device 61 inputs the outputs of the multiplier 45 and the gain calculating devices 49 and 57 and outputs their minimum value as an upper and lower limit limit value LMT (I *) for the current command.

The current command calculator 21 inputs the upper and lower limit limit LMT (I *) for the current command output from the temperature monitor 20 , and limits the upper and lower limit of the absolute value of the preset current command I * to LMT (I *) , which is then output to the current control device 22 as the set current command I **.

The current control device 22 outputs and generates a switching signal (gating signal) for each switching element, so that the current of the motor 2 can follow the current command I **. Since a calculation method for the current command in the current command calculator 21 and a current control method and a switching signal generation method in the current control device 22 are not special to the present invention, but many other methods are known and are available to the public, no further description is given here .

As described above according to the seventh Embodiment the switching element temperature and Current command value on the motor are designed to be in it can be monitored in a chronological order possible, the switching element with a suitable Protection against overheating according to the extent of the temperature rise Mistake. Furthermore, since the failure of the Temperature sensing diode, breaking the Temperature information signal line and the like can be detected automatically and as a result the Motor movement can be changed moderately, it is effectively that the continuity of control and the characteristic stability of the vehicle ensured become.  

Eighth embodiment

An overheating protection function of the engine can be added to the seventh embodiment. Namely, a temperature monitoring form of the eighth embodiment also inputs an engine temperature signal from an engine temperature sensor 70 as shown in FIG. 10. In addition to the structure in FIG. 8, the temperature monitor 20 is designed to input and process the temperature information of the motor 2 , as shown in FIG. 11.

The operation of the embodiment will now be as follows explained.

The operation common to Fig. 8 is omitted here.

When the temperature Tmt of the engine 2 is detected from the engine temperature sensor 70 and input to the temperature monitor 20 , the value Tmt is subtracted from the constant Tmax_MT from the constant output means 71 in the subtractor 72 to output an engine temperature margin Tmtmargin. Here, the constant Tmax_Mt is set to a value corresponding to a temperature that overheats and damages the motor 2 . Then, the motor temperature margin Tmtmargin is multiplied by a gain Kc in the coefficient multiplier 73 and output as a value corresponding to the upper and lower limit limit of the current to be sent to the motor 2 . That is, the current is designed to be limited according to the value of the motor temperature margin Tmtmargin, and the gain Kc is determined by the amount of the temperature rise of the motor 2 relative to an amount of current, heat radiation behavior, and the like. Furthermore, the total sum Σ | I * | from | I * | (n-1), | I * | (n-2),. . . | I * | (nm) and | I * | (n) output from the adder 32 is input to the gain calculation card 74 and a setting gain amount that corresponds to the amount of the total Σ | I * | is output. The adjustment gain amount is set to 0 or a small value when the total Σ | I * | is small, and is set to a higher value when the total Σ | I * | is bigger. Furthermore, the constant 1.0 is output by the constant output device 75 . In the subtracter 76, the output of the gain calculation map 74 is subtracted from the constants 1.0 and entered. Here, multiplying {(1.0- (output of the gain calculation card)} corresponds to setting the value corresponding to the upper and lower limits of the current to be sent to the motor 2 with respect to the motor temperature margin according to the amount of the total Σ | I * | of the absolute value of the preset current command I * for the period of the past m × Δt. Namely, the larger the amount of the total sum Σ | I * |, the smaller the upper and lower limit limit of the current.

Next, the minimum value output means 61 inputs the outputs of the multipliers 77 and 45 and the gain calculating means 49 and 57 and outputs the smallest value thereof as the upper and lower limit limit LMT (I *) for the current command. The current command calculator 21 inputs the upper and lower limit limit LMT (I *) for the current command being issued from the temperature monitor 20 , and limits the upper and lower limit of the absolute value of the preset current command I * to LMT (I * ) and outputs this to the current control device 22 as the set current command I **.

The current control device 22 outputs and generates the switching signal (gating signal) of each switching element, so that the current of the motor 2 can follow the current command I **.

According to the above structure, overheating protection of the Switching element and the motor possible.

Ninth embodiment

In addition to the structure where the temperature is up Basis of the forward voltage of the temperature detection diode another structure is shown here, the one with a device for detecting the collector-to-emitter Voltage of a bipolar transistor is provided as the switching element is used and the the current value that to the Switching element is sent, calculated.

The ninth embodiment will be explained below with reference to FIGS. 12 and 13.

In Fig. 12, reference numeral 80 is a Vce voltage detector for detecting the collector-to-emitter voltage of the switching element, and reference numeral 81 is a current value calculator for calculating the current value sent to the switching element based on the Collector-to-emitter voltage detected by the Vce voltage detector.

The principle of operation for detecting the current supplied to the Switching element should be sent, according to the ninth Embodiment is explained below.

Fig. 13 shows the characteristics of a collector current Ic of the switching element, and a collector-to-emitter saturation voltage Vce (sat). Sufficient voltage is applied to a gate G of the switching element to use the switching element in a saturation region. When the switching element is turned on to send the collector current Ic, a voltage Vce (sat) is generated between the collector C and the emitter E. In this case, the characteristic of an amount of the collector-to-emitter saturation voltage Vce (sat) changes relative to an amount of the collector current IC change depending on the transition temperature Tjsw of the switching element and the voltage applied to the gate G is created, but are inherently determined by the switching element. Accordingly, if the voltages applied to the gate G and the transition temperature Tjsw are already known with these characteristics, it is possible to extract the collector current Ic, i.e. the current value sent to the switching element, from the collector -to detect emitter saturation voltage Vce (sat).

The operation of this embodiment will be as follows explained.

The collector-to-emitter voltage of the switching element is detected by the Vce voltage detector 80 and output to a current value calculator 81 as the collector-to-emitter voltage signal. Furthermore, a constant forward current, if it is fed to the temperature detection diode 19 a by a constant current circuit 18 , and the forward voltage vf of the temperature detection diode 19 a of the overheating identification device 8 is entered. The overheat identification device 8 outputs the switching element temperature signal Tj to the current value calculation device 8 based on the forward voltage vf. When the collector-to-emitter voltage signal and the switching element temperature signal Tj are input, the current value calculator 81 calculates the current (corresponding to the collector current Ic) to be sent to the switching element based on the characteristics of the collector current Ic and the collector-to-emitter saturation voltage Vce (sat) as shown in FIG . It is advisable to have the current value calculator 81 store the characteristics of the collector current IC and the collector-to-emitter saturation voltage VCe (sat) including the dependency on the switching element temperature Tj in the form of an approximate calculation formula or a reference table map.

This makes it possible to measure the current value that is applied to the switching element to be sent quickly and accurately.

In the ninth embodiment, an FET for Switching element used. It is also possible to get one Voltage detection device for detecting a Drain voltage (output terminal voltage) of this FET and means for calculating the current value applied to the Switching element is sent to provide.

In Fig. 12 of the ninth embodiment, the overheating protection device 9 is not provided, but it is of course possible to provide the overheating protection device with the overheating protection device 9 . Furthermore, in each embodiment it is possible to use the PN junction of the transistor instead of the temperature detection diode. The semiconductor element with the PN junction can be arranged in the vicinity of the switching element.

Furthermore, it is also possible to use the FET as the switching element in to use any embodiment. In this case a source and a source voltage can be controlled.

As described above, according to the engine control unit of the present invention, the semiconductor element including the P-N junction near the Arranged switching element and this semiconductor element is  connected to a constant current circuit. The temperature of the switching element can by detecting the Forward voltage value in the P-N junction of the Semiconductor element can be recognized. The overheating Protection is provided to switch the switching element in bring an OFF state if based on the detected switching element temperature is judged that the switching element is in an overheating condition. According to this structure, it is possible to Switching element temperature, which is the power element of the Power conversion semiconductor forms, quickly and accurately detect and further it is possible to switch the element in front to protect against overheating.

So that the movement of the motor is moderate in the event of a Failure of the semiconductor element or a wire break can change, the tax calculation unit is provided. The tax calculation unit is with the Monitoring device for controlling the current command value Mistake. In addition to this effect, the Engine control unit an advantage in that the Continuity of a control is ensured.

The engine control device is provided in which both the Temperature as well as the overheating protection of the engine have been taken into account.

The tax calculation unit is with the Current calculation device provided that the current value, the is sent to the switching element based on the Temperature and the output terminal voltage value of the Switching element can calculate. With this arrangement it is possible the current value sent to the switching element will calculate quickly and accurately.

Claims (12)

1. Motor control unit comprising: a first switching element ( 5 a), which is arranged on a high potential side; a second switching element ( 5 b) which is arranged on a low potential side; a multiple phase of switching arms which connect the first switching element and the second switching element together in series and which are connected to a DC power input to supply an AC motor ( 2 ) with AC power between each switching element of each switching arm; a control calculation unit ( 3 ) for controlling the switching operation of each switching element to control the current of the motor; and
a semiconductor element ( 19 ) having a PN junction located near the switching element and connected to a constant current circuit ( 18 ), and an overheating protection device ( 8 , 9 ) being provided to detect the temperature of the switching elements by detecting a forward voltage value between the PN junction of the semiconductor element and bringing the switching element into an OFF state when it is judged based on the detected temperature of the switching element that the switching element is in an overheating condition. 2. Engine control unit comprising:
a first switching element ( 5 a), which is arranged on a high potential side;
a second switching element ( 5 b) which is arranged on a low potential side;
a multiple phase of switching arms which connect the first switching element and the second switching element together in series and which are connected to a DC power input to supply an AC motor ( 2 ) with AC power from between each switching element of each switching arm;
a control calculation unit ( 3 ) for controlling the switching operation of each switching element to control the current of the motor; and
a semiconductor element ( 19 ) having a PN junction located near the switching element and connected to a constant current circuit ( 18 ); an overheat protection device ( 8 , 9 ) is provided to detect the temperature of the switching element by detecting a forward voltage value between the PN junction of the semiconductor element and to bring the switching element into an OFF state when based on the detected temperature of the switching element it is judged that the switching element is in an overheating condition; and
wherein the control calculating unit ( 3 ) further includes current command value calculating means ( 21 ) for calculating a current command value sent to the motor, current control means ( 22 ) for controlling the current sent to the motor based on the current command value, and monitoring means ( 20 ) for Entering the temperature of the switching element and the current command value, for monitoring the relationship between the switching element temperature and the current command value in a time sequence, and for controlling the current command value to cause the motor to move in the event of a failure, for example damage to the semiconductor element or a broken wire that changes moderately. 3. Motor control unit according to claim 2, characterized in that instead of the monitoring device, another monitoring device ( 20 ) for entering the motor temperature, the switching element temperature and the current command value, for monitoring the relationship between the motor temperature, the switching element temperature and the current command value in a chronological sequence, and for controlling the current command value to cause the movement of the motor to change moderately in the event of a failure, for example damage to the semiconductor element or a wire break. 4. Engine control unit comprising:
a first switching element ( 5 a), which is arranged on a high potential side;
a second switching element ( 5 b) which is arranged on a low potential side;
a multiple phase of switching arms which connect the first switching element and the second switching element in series and which are connected in parallel to a DC power input to supply an AC motor ( 2 ) with AC power from between each switching element of each switching arm; a control calculation unit ( 3 ) for controlling the switching operation of each switching element to control the current of the motor; and wherein a semiconductor element ( 19 ) having a PN junction is arranged in the vicinity of the switching element and connected to a constant current circuit ( 18 ); wherein detection means ( 8 ) is provided for detecting a forward voltage value between the PN junction of the semiconductor element and detecting the temperature of the switching element, and voltage detection means ( 80 ) is provided for detecting an output terminal voltage value of the switching element, and wherein the control calculating unit ( 3 ) is further provided with a current calculating means ( 81 ) for calculating a current value sent to the switching element based on the switching element temperature and the output terminal voltage value of the switching element. 5. Motor control unit according to claim 4, characterized in that an overheating protection device ( 8 , 9 ) is provided in order to bring the switching element into an OFF state when judging on the basis of the switching element temperature which is recognized by the detection device, that the switching element is in an overheating condition. 6. Motor control unit according to claim 1, characterized in that the overheating protection device ( 8 , 9 ) is designed to previously store the forward voltage value of the semiconductor element at a fixed temperature so that it can recognize changes in the switching element temperature as the absolute variable. 7. Motor control unit according to claim 1, characterized in that the overheating protection device ( 8 , 9 ) is designed to transmit the switching element temperature to the control calculation unit in the form of an analog signal. 8. Motor control unit according to claim 1, characterized in that the overheating protection device ( 8 , 9 ) is designed such that it sends information about whether the overheating protection of the switching element is currently being carried out or not to the control calculation unit in the form of a digital signal issues. 9. Motor control unit according to claim 1, characterized in that the overheating protection device ( 8 , 9 ) is designed to detect the highest temperature of each phase of the switching element and to carry out an assessment based on this highest temperature. 10. Motor control unit according to claim 1, characterized in that the semiconductor element ( 19 ) is arranged inside or near a chip area where the switching element is formed. 11. Motor control unit according to claim 1, characterized in that a diode ( 19 ) is used for the semiconductor. 12. Motor control unit according to claim 4, characterized in that a bipolar transistor is used for the switching element ( 5 a, 5 b) and the voltage detection device ( 80 ) detects the collector-to-emitter voltage value of the bipolar transistor.